Amino acid composition and nitrogen-to-protein conversion factors for sweet potato

Abstract

Protein contents of ten sweet potato varieties ranged from 1.3 to 3.1 g% dry weight. Intervarietal differences in amino acid profiles were observed, particularly in the levels of aspartic acid, glutamic acid, leucine and lysine. Based on nitrogen recovered front amino acid analyses, the nitrogen-to-protein conversion factor averaged 6.19(±0.07), close to the assumed 16% nitrogen content of proteins. The varieties also contained different amounts of non-protein nitrogen, so the use of the 6.25 factor with total nitrogen would give serious errors. Based on data from ten sweet potato varieties, the Kjeldhal nitrogen: protein factor averaged 3.59(±0.27).